Duramax comprises 6.6L diesel engines designed by General Motors but are manufactured by DMAX, a joint venture between Isuzu and GMC.
These engines are known for their reliability and smooth operation due to the inclusion of a timing gear.
However, they face some serious problems!
What Year Duramax Has Problems?
Generally, you should avoid the first-generation Duramax engine (2001 to 2004). This engine lacks exhaust gas recirculation (EGR) and diesel particulate filter (DPF), and they’re likely to experience EGR valve issues, overheating, and head gasket failure.
So, when searching for a Duramax engine, every year has different problems to watch out for. Duramax engines from 2010 have undergone significant improvements, so you should expect them to offer better reliability than their predecessors.
Read on to learn more about Duramax and the common problems over the years.
Which Year Duramax Has Issues With the Head Gasket?
Duramax engines between 2006 and 2010 have riveted gaskets that caused them to leak internally, especially when they fail.
In case this problem arises, you’ll see a coolant puddle on the ground when you park your truck overnight.
Which Year Duramax Has Issues With the Injector?
It’s not easy to say for sure the specific years when Duramax had injector problems.
However, the first generation of Duramax engines had serious injector problems.
So, it’s worth purchasing an injector with the manufacturer’s update if you’re using the first Duramax engine (LB7).
Which Duramax Engine Is Safe to Buy Used?
Since GM began the production of Duramax engines in 2001, there have been many changes to their engine design that have affected performance.
That said, on your search for a second-hand Duramax engine you can rely on, you’re better off with the L5P Duramax engine.
This engine production began after 2011, and the manufacturer designed it to meet the new emission regulations.
The only slight problem with this engine is that they have weak tie rods that can go bad if you’re sled-pulling or drag racing.
Which Duramax Engine Is Most Reliable?
The most reliable and efficient Duramax engine overall is the Duramax LB7. Remember that your Duramax diesel engine can attain 350,000 miles with proper maintenance.
Some users even claim that their engine can hit over 400,000 miles.
Besides minor concerns like injector issues, you can count on the LB7 to serve you for a long time.
Common Duramax Issues by Year
Some Duramax engine issues are limited to specific models, but some spread across different years of production.
It’s easy to address some of the problems by purchasing aftermarket upgrades, but the guaranteed way to guarantee your engine’s reliability is to inspect and maintain it regularly.
Let’s dive into the common problems Duramax engines have experienced over the years.
LB7 Duramax Engines (2001 to 2004)
Despite the lack of emission control parts, this engine model is popular among many diesel enthusiasts.
Another notable issue is that they experience injector fuel issues, particularly when they hit 100,000 miles.
However, if you wish to replace it, Duramax has upgraded the original injectors to address this issue.
Other common problems with the Duramax LB7 include:
- Head gasket failure
- Leaks on the water pump
- Leaks on the fuel filter housing
- Lack of a factory lift pump
LLY Duramax Engines (2004 to 2006)
This Duramax engine was in production for a short time and had a lot of similarities to the LB7, including the lack of emission control parts.
Before the release of this engine, GM had addressed injector issues.
However, it faces new challenges like overheating when driving in hot temperatures or towing a heavy load.
This mostly happens because of problems with the stock air intake system.
Again, the original turbo mouthpiece was too restrictive, causing the engine to run hotter. Most people facing this issue resort to using Duramax aftermarket parts like aftermarket turbo inlet or cold air intake.
The other common problems with this engine include:
- EGR valve issues
- Water pump failure
- Head gasket failure
- Injector harness chafing
- Missing factory lift pump
LBZ Duramax Engines (2006 to 2007)
This Duramax engine generation is considered the best Duramax engine built for different reasons.
Unlike the previous generation, this Duramax engine featured a six-speed Allison transmission.
General Motors also fixed the common bugs found in the past models.
The only minor concern is that GM didn’t install a factory lift pump.
Regardless, this is a simple fix that doesn’t require a lot of upfront investment.
If you’re hoping to exceed the 600 horsepower, it’s worth investing in mods because you may encounter issues with piston cracking.
LMM Duramax Engines (2007 to 2010)
The inception of LMM engines coincided with changes in regulation for emission control parts.
The LMM Duramax was similar to LBZ in different ways but with the inclusion of emission control parts which the LBZ didn’t have.
The primary area of concern with the LMM is that its pistons are prone to breakage because of the injector setup.
Unlike the LBZ, which has seven fuel spray fuels, the LMM has six, meaning that two streams of fuel are coming from the opposite direction.
This causes hotspots to form on the weakest parts of the piston, resulting in cracks.
LML Duramax Engines (2011 to 2016)
The LML Duramax engine has significant design improvements from the previous models.
For instance, they increased the power output to 400 horsepower with a 765 torque.
Additionally, General Motors had to increase the fuel system pressure for the engine to achieve this type of power output without compromising on emission.
This change has brought about different problems in some engines.
The most common is that some engines experience unexpected fuel pump failure resulting from metal shaving spreading within the fuel system.
You’ll need to invest in a new fuel system kit to address this failure, including fuel rails, injectors, and fuel filters.
You’ll still need to drop the tank to clean the metal debris effectively.
Another solution to this concern is installing a lift pump that offers better debris and air filtration.
Some LML engine owners still prefer installing the Bosch CP3 found in the LB7 engine.
While it suffers from low pressure, it still delivers more horsepower.
L5P Duramax Engine (2017 to Present)
This Duramax engine has been revered as the best post emissions.
This model has addressed some of the common issues it has faced throughout the years, like emission system and injector pump problems.
Generally, this engine provides excellent reliability and performance, and users have reported minor issues concerning its usability.
A notable concern is that the vehicle MAP sensors sometimes become clogged with soot, triggering the check engine light.
You can efficiently resolve this problem by installing a MAP sensor spacer and using an electrical cleaner to remove the soot.
Regardless of the year Duramax you wish to purchase, they’ll always have their challenges. Luckily, it’s easy to address some of the issues your engine experiences by using aftermarket mods.
When having trouble choosing one type of engine over the other, it all comes down to what you need.
For instance, LMM is almost similar to LBZ, with the only difference being the emissions control parts.
Regarding aspects like stock engine, the LML and LLY are known to be problematic.